Experimental investigation on mechanical behavior of 3D integrated woven spacer composites under quasi-static indentation and compression after indentation: Effect of indenter shapes.

This paper presents an experimental study on the mechanical response of 3D integrated woven spacer carbon fiber composites under quasi-static indentation (QSI) and the failure behavior under compression after indentation (CAI). The test specimens are divided into weft direction ones (X-type) and warp direction ones (Y-type). The quasi-static indentation process is conducted using four types of indenters: the hemispherical indenter, the flat indenter, the conical indenter, and the pyramid indenter. A C-scan ultrasonic imaging system and a digital microscope are used to evaluate the damage visibility and penetration resistance of 3D integrated woven spacer composites during the QSI test. The digital image correlation (DIC) is used to perform the CAI analysis. The results indicate that the flat indenter has the largest indentation damage area (395 mm2 for X-type specimens, 398 mm2 for Y-type specimens), and the average indentation damage area caused by the four indenters is less than twice of the maximum cross-sectional area of each indenter. The maximum absorbed energy of two types of 3D integrated woven spacer composites is very similar in QSI tests under the same indenter. It is found that the residual strength of the X-type specimen decreases by 51.7% and that of the Y-type specimen decreases by 35.8% after the flat indenter penetrates the specimen. • The QSI response of the carbon fiber 3D integrated woven spacer composites is experimentally investigated. • The residual properties and failure mechanism of 3D integrated woven spacer composite under weft and warp compression are experimentally investigated. • The 3D integrated woven spacer composite exhibits good interlayer performance and a high level of damage tolerance. • X-type specimen has higher compression stiffness and residual compressive strength than the Y-type specimens. [ABSTRACT FROM AUTHOR]